The subject matter disclosed herein generally relates to rotary wing aircraft. More specifically, the subject disclosure relates to tail rotors, or propulsors for rotary wing aircraft.
A rotary wing aircraft includes one or more main rotor assemblies to provide lift and propulsive thrust. To provide additional thrust, the tail rotor, typically oriented with an axis of rotation perpendicular to the tail of the aircraft is oriented instead so its axis of rotation is along a forward to aft axis of the aircraft. In this orientation, the tail rotor acts as a pusher propeller or propulsor, providing additional forward thrust to the aircraft. The propulsor tends to be highly loaded, however, due to propulsor diameter and weight constraints, with the load a function of shaft horsepower input divided by a square of the diameter. The resulting propeller blades have a high angle of attack to the free stream air compared to a large diameter propeller blade at the same shaft horsepower to withstand the loading. The higher angle of attack results in significant losses of cruise propulsive efficiency.